Lore

The man known as Salaman came from the Great Swamp with an unknown objective.

According to Quelana, around 200 years before the events of Dark Souls 1 she took Salaman as her first pupil. She taught Salaman the art of pyromancy with good results, despite her describing him as a bungling man.

It is believed that Salaman returned to the Great Swamp, where he was quickly called 'Master Pyromancer thanks to his new abilities. He took pupils, Carmina being the most accomplished one.

He also received the nickname 'Great Fireball' in regards of the spell he either used or created.

The name 'Salaman' could be made parting from the /Salamander/, which is one of the multiple mythological beings of fire.

Artistically, Hidetaka Miyazaki shared some words in 2011 about Salaman:

Salaman is a character that has an important role, along with the witches of Izalith, in the story of pyromancy rather than in the story of Dark Souls.
Salaman’s story was created to introduce a concept of pyromancy but only his name appeared in the original story.
His visual image has actually been created and he is one of my favourite characters.

Theories

Theory Title

Sources

Quelana of Izalith DialogueLong ago, I accepted another pupil, like yourself.
Over two-hundred years ago, there was a man, almost as bungling as you…
… in your world he was called Salaman the Master Pyromancer.
The little rascal really made something of himself.

Great FireballSalaman the Master Pyromancer, also called the Great Fireball after this spell, believed pyromancy was rooted in an adoration of fire.

Flash Sweat, Iron Flesh, Power WithinCarmina, the most accomplished pupil of Salaman the Master Pyromancer, pioneered new directions for the art of pyromancy.